Figure 1
A: Conventional anteroposterior and lateral radiography of the left knee of a male schoolchild with knee pain. Extensive centric and metaphyseal lytic lesion expanding the cortical bone, with well-defined boundaries, a short transition zone, an adjacent sclerotic rim, and intralesional streaks of fibrotic bone, consistent with a simple bone cyst. There is a fracture with callus formation (arrows). B: Conventional radiography of the right knee of a male schoolchild shows the same findings, consistent with simple bone cyst. C: Extremely expansile, metaphyseal, lytic lesion, with a short transition zone and no sclerotic rim, with discrete intralesional streaks of fibrotic bone and not invading the growth plate, located in the proximal third of the left fibula (arrow) of an adolescent with knee pain. The findings are characteristic of an aneurysmal bone cyst.
Figure 2
Conventional anteroposterior radiography (A) and conventional lateral radiography (B) of the left knee of an adult with mechanical knee pain. Well-defined, metaphyseal, lytic lesion on the distal femur, with an adjacent, reactive sclerotic rim (arrows), not breaking through the cortical bone. Characteristic "ground glass" aspect. There are also findings consistent with degenerative joint arthropathy, which may be the cause of the pain described by the patient.
Figure 3
Conventional anteroposterior radiography (A) and conventional lateral radiography (B) of the left knee of a female patient with systemic lupus erythematosus and joint pain. The imaging shows a lesion with a mixed, heterogeneous radiological pattern in the medullary bone of the distal femur, with imprecise boundaries and a geographical aspect (arrows), although not breaking through the cortical bone. Tapered cortical bone can also be observed throughout the femur evaluated. Together with the clinical history, the MRI findings and the low concentration of radiopharmaceuticals on scintigraphy indicate bone infarction. The anatomopathological examination confirmed the diagnosis.
Figure 4
A: Anteroposterior and lateral conventional radiography of the right knee of a female adolescent, who presented with progressive pain and localized swelling, showing an aggressive mixed metaphyseal lesion, characterized by imprecise boundaries, Codman's triangle periosteal reaction (thin arrow), invasion of the cortex, and formation of a "bone outside the bone"aspect (thick arrow). B: Mixed metaphyseal lesion in the proximal left tibia, with a "sunburst" image (arrow) as well as a periosteal reaction resulting in the formation of Codman's triangle.
Figure 5
A: Patient with open physes, showing mixed sessile lesions in metaphyseal region of the distal femur and proximal tibia, with aspect of normal bone, characteristic of osteochondromas (arrows). B: Typical adult osteochondromas that tend to spread out from the joint. Note the extensive posterior lesion in the tibia and fibula (arrows), which causes pain by compression and limits joint mobility.
Figure 6
A previously asymptomatic young adult with a pain episode and acute limitation of right knee mobility after a common trauma. Anteroposterior conventional radiography of the knee (A) showing a small, rounded lytic lesion, with small intralesional foci of calcification, precise boundaries, and no sclerotic rim, in the distal femur (arrow), accompanied by evidence of a metaphyseal fracture (arrow in B) centered on the lesion, extending to the joint, characterizing a pathological bone fracture.
Figure 7
A: A 10-year-old patient with progressive pain and swelling of the right knee. Black and white arrows indicate an oval-shaped, osteolytic epiphyseal lesion with a sclerotic rim, not breaking through the cortex, with intralesional foci of calcification, in the medial condyle of the femur. There are also signs of joint effusion characterized by distension of the suprapatellar bursa. B: A 17-year-old adolescent, showing closed physes and the same clinical complaints. Black and white arrows mark the lesion with the same radiological characteristics.
Figure 8
A 14-year-old patient with progressive pain and localized swelling in the right knee. Anteroposterior and lateral radiological studies (A and B, respectively), showing a metaphyseal lytic lesion in the distal femur, extending to the epiphysis, with a discrete, reactive sclerotic rim, and breaking through the cortex in the lateral condyle of the femur (arrows).
Figure 9
Radiograph of an adult with knee pain showing an aggressive, mixed metaphyseal lesion in the distal femur, with various foci of confluent calcification. The lesion is breaking through the cortex, with calcification also in the soft tissues (arrow).
Figure 10
A 9-year-old male patient with pain and a large mass in the right thigh. A: Anteroposterior radiography of the left femur showing an essentially lytic metadiaphyseal lesion (arrow), an undefined zone of transition, increased density in the soft tissues, and destruction of the bone cortex. B: The same characteristics are seen with the formation of a Codman's triangle periosteal reaction (arrow). Radiologically aggressive lesion.
Figure 11
A 50-year-old patient with knee pain and radiological findings indicating an aggressive lesion. Anteroposterior radiography of the knee, showing tapering of the cortical bone in the proximal tibia, presence of a mottled, mixed medullary lesion with an imprecise zone of transition, extending from the subchondral boné to the diaphysis. The main differential diagnosis is metastasis, hyperparathyroidism, and lymphoma. Laboratory tests confirmed the diagnosis of multiple myeloma.
Figure 12
A: Anteroposterior and lateral radiography of an adolescent who suffered direct trauma on the knee region. Well-circumscribed lytic lesion (arrows) in the metaphyseal region of the fibula, not breaking through the cortex but extending to the bone marrow, with a sclerotic rim. Painless lesion, consistent with nonossifying fibroma. B: Lesion with similar characteristics (arrows) observed in the anterolateral region of the proximal tibia; the lesion is smaller and more wellcircumscribed in the cortical bone, not extending to the bone marrow, and is therefore designated a fibrous cortical defect. The lesions are histologically identical and do not show radiological characteristics indicative of aggressive lesions.
Figure 13
A: Anteroposterior and lateral radiography of the right knee of a female patient with a primary breast tumor. Metaphyseal lytic lesion on the tibia, with an imprecise zone of transition and ill-defined borders (arrows). B: Another case of a female patient with a primary breast tumor, who presented with knee pain. The image shows radiological features of aggressiveness, characterized by lytic lesion on the distal left femur, which breaks through the cortical bone (arrows), invades the adjacent soft parts, without a sclerotic rim and with an imprecise zone of transition. There are also lesions in the medial condyle of the fêmur and proximal third of the tibia.
Figure 14
A: Adult female patient with recent knee pain; radiography shows an eccentric epiphyseal lytic lesion in the medial condyle of the tibia, without a sclerotic rim, with a narrow zone of transition, and without a periosteal reaction or invasion of soft tissues (arrows). B: Radiography of another patient with closed physes, showing a painful epiphyseal eccentric lytic lesion that expands and thins the cortical bone in the lateral condyle of the femur (arrow), extending to the subchondral bone. C: Lateral radiography of the knee in another case, with an epiphyseal lytic lesion that thins and breaks through the anterior cortical bone. All findings are consistent with a giant cell tumor in distinct phases of evolution.
